75 lines
1.4 KiB
C
75 lines
1.4 KiB
C
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#include <assert.h>
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#include <pthread.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <time.h>
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static inline double tstamp(void)
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{
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struct timespec tv;
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clock_gettime(CLOCK_REALTIME, &tv);
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return tv.tv_sec + tv.tv_nsec * 1.0e-9;
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}
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typedef struct thread_arg
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{
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long int start;
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long int limit;
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long int inc;
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long int S;
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} thread_arg;
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void *slice(void *arg)
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{
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thread_arg *a = (thread_arg *)arg;
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long int S = 0;
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for (long int i = a->start; i <= a->limit; i = i + a->inc)
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{
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S += i;
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}
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a->S = S;
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return NULL;
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}
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int main(int argc, char *argv[])
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{
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long int N, M, S = 0;
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thread_arg *args;
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pthread_t *ths;
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double t1, t2;
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assert(argc >= 3);
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N = strtol(argv[1], NULL, 0);
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M = strtol(argv[2], NULL, 0);
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t1 = tstamp();
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args = (thread_arg *)calloc(M, sizeof(thread_arg));
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assert(args != NULL);
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ths = (pthread_t *)calloc(M, sizeof(pthread_t));
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assert(ths != NULL);
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for (int i = 0; i < M; i++)
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{
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args[i].inc = M;
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args[i].limit = N;
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args[i].start = i + 1;
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pthread_create(ths + i, NULL, slice, (void *)(args + i));
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}
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for (int i = 0; i < M; i++)
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{
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pthread_join(ths[i], NULL);
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S += args[i].S;
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}
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assert(S == N * (N + 1) / 2);
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t2 = tstamp();
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printf("S = %ld\n", S);
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printf("t = %lf\n", t2 - t1);
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return 0;
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}
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